The present invention relates to an electrical test probe tip (“probing tip”), and more particularly to a bendable conductive connector.
FIGS. 1 and 2 show a probing system that includes an electrical test probe 20 for providing an electrical connection between electrical components 22 and testing instruments 24. An electrical test probe 20 generally consists of a cable 32 having a probing head 30 at one end and a testing instrument connector 34 at the other end for attaching the cable to testing instruments 24 (e.g. oscilloscopes and other measuring, monitoring, diagnostic, and signal processing instruments). The probing head 30 generally is interconnectable with at least one probing tip, which may be a removable and/or replaceable probing tip 40. A socket 38 or other connection means may be used for connecting the probing tip 40 to the probing head 30. One or more of the probing tips 40 may be used, for example, for making electrical contact with testing points 22 (e.g. pins, leads, paths, or other electrical components) such as those found on a circuit board. One or more of the probing tips 40 may be used as a means for connecting the probing head 30 to ground. Ground provides the electrical reference point for other signal measurements, so the ground connection typically remains unchanged while the probing head is positioned at testing points so that the electrical signal thereon may be measured, monitored, or otherwise processed.
It is difficult to form a contact with modern miniaturized testing points. For example, both the pins and the spacing between the pins on a modern integrated circuit chip (“IC”) have been miniaturized. If two adjacent pins are contacted simultaneously by the probing tip, a short circuit may result between the two adjacent pins. A short circuit may prevent measurement of the desired signal and may result in damage to the internal circuitry of the IC.
Most probing tips are stiff. For example, a traditional probing tip is a stiff conductive member that terminates in a conical, blunt, or rounded point. IC grabber probes have a jaw-like tip that connects to and holds a pin, but are also relatively stiff and prevent optimum positioning of probing heads.
Tektronix, Inc. produces a signal-ground adapter that has been specifically designed to connect with a square pin. But like the IC grabber probes, the signal-ground adapter connects rigidly to signal and ground pins, and the inflexibility prevents desirable movement of the probing head to optimum positions. Tektronix also produces a right-angle adapter that includes a stiff coil used to rigidly attach a probe at a right angle to a pin. The purpose of the stiff coil is to mate with a pin, and the stiffness prevents movement of the probe. Because it is inflexible after mating with the pin, the coil is not adaptable and may be used in only one position for probing a specific type of pin (a 0.025 inch diameter square pin). Tektronix also produces a “Y-lead” adapter that has wire leads that may be combined with the right-angle adapter. The combination of the right-angle adapter and the Y-lead adapter may allow the probing head to be moved relative to the device being probed, but the addition of leads may add inductance. Probing an electrical device using the Y-lead adapter may be inconvenient or impossible using just one hand. Typically, the probe body must be laid on the table while pin connections are changed. Draping the wire leads on electrical components and moving parts, such as a CPU fan, is another disadvantage of the Y-lead adapter.
Several prior art references are directed to electrical test probe tips and electrical connectors. U.S. Pat. No. 4,978,312 to Fodali (the “Fodali reference”) is directed to a tip attachment for a circuit test probe and, specifically, to a spring attachment for placement on a handheld tester with an ice pick-type probe. One end of the tapered spring tip attachment fits on the ice pick-type probe, and the other end terminates in a straight length of wire. The purpose of this spring attachment is to provide a smaller gauge tip for insertion into sockets too small for the ice pick probe. In other words, the Fodali tip uses a spring merely as a connector for attaching the straight wire probe end to a tapered ice pick-type probe.
U.S. Pat. No. 3,885,848 to Brouneus (the “Brouneus reference”) is directed to a method of making an electrical connection with a flat surface contact using a conical spring. The contact member is a conically spiraled length of electrically conductive resilient wire including spirals that progressively increase in size. A cylindrical helix is electrically connected to the small end of the volute helix. An electrically conductive terminal member may be inserted into and secured within the cylindrical helix. The wide end of the conical spring may be electrically connected to a flat conductive surface. Compressing the volute helix moves the spirals of the helix into contact with a flat surface. The volute helix would return to its original position if not held in place.
Problems with exemplary ground connections include, but are not limited to, that they do not hold themselves in place, they are not able to be used in an axial application, they have poor compliance, they have poor or little radial adjustment, they have poor axial compliance, and they are not adjustable or are only adjustable in one direction.